Seasonal variation in morphology of continuously stocked white clover

Efforts to improve persistence of white clover (Trifolium repens L.) in the southeast USA would benefit from knowledge of annual growth patterns and associated periods of environmental stress. Our objective was to determine seasonal changes in morphological traits that contribute to plant growth and persistence among adapted cultivars and germplasm. 'Louisiana S-1', 'Osceola', Brown Loam Synthetic No. 2 germplasm, and Southern Regional Virus Resistant germplasm were sown in common bermudagrass [Cynodon dactylon (L.) Pers.] pastures in September 1993 at Mississippi State and Newton, MS, and continuously stocked with cattle to maintain a 5- to 10-cm sward height. Stolon length, viability of axillary buds, and seedling numbers were measured monthly for the next 2 to 3 yr. Stolon length of all entries increased to a maximum by June before declining to a minimum in October. Peak stolon production in the first, second, and third year after seeding at Mississippi State was 42, 123, and 59 m m-2, respectively. There were no monthly differences among the four entries for proportion of stolon nodes having elongated, viable, or nonviable axillary buds at either location. The proportion of nodes with elongated buds increased from 10 to 20% in October to 45% in March before declining during the spring. An increase in elongated buds during early summer preceded the fall decline. Number of volunteer seedlings ranged from 10 to 1870 m-2 during the year, but any positive influence on stand persistence was not apparent. The cyclical trends for axillary bud viability indicate continued potential for vegetative persistence, particularly in the winter and spring, but the long-term decline in stolon length of all entries suggests that selection for different characters was not associated with improved persistence